Can a freeze plug pipe isolation be achieved
on a pressurized piping system ?
Yes! In many cases freeze plugs created within a
pressurized pipe are more solid than a plug which is
created under non-pressurized conditions. This is
due in part to the fact that the internal piping
fluid molecules are more dense under pressure, thus
creating a more dense freeze plug at a faster rate.
Can a pipe with flow be freeze plugged 100% ?
NO! During the winter months when there is a
threat of a hard freeze, most people crack open a
faucet to create a small amount of flow in order
to prevent the pipes from freezing solid. So in
order for either mother nature or NC Pipe Freeze
to freeze plug a section of your piping system it
must be in a no flow condition.
If the pipe in question can only be freeze
plugged while it is in a no-flow situation why do I
need your services ?
Good question! The following illustrates a typical
scenario of when you might need us for a freeze
plug.
Lets say you have a pump that needs maintenance and
you've tried to valve it out with no success. The
inlet / suction valve is operating normal, but the
outlet / discharge valve is stuck in the open mode,
preventing a 100% pump isolation. We'd make the
freeze plug downstream from the discharge valve and
the suction valve which operates normally would hold
the flow on the other side of the pump, thus
allowing the freeze plug to materialize creating an
isolation so you could change out the bad discharge
valve. If necessary, double simultaneous freeze
plugs could be made so that both valves could be
changed out.
How long does it take to freeze plug a pipe ?
Two of the most prevalent factors in achieving a
freeze plug is the pipe size and system temperature
at the time of the freeze. The following would be a
good example. Using the CRYOSTOP technology a 6"
schedule 40 pipe @ 70 degrees would take
approximately 55 to 65 minutes to achieve a solid
workable plug.
What are the pressure limits ?
Workable freeze plugs have been developed on pipes
where the system pressure was as high as 2250 psig.
Tests have also been performed on pipe, where the
system pressure of the pipe was increased 10,000 psi
above the rated failure point of the piping
material. Although the pipe yielded at a point away
from the freeze plug, the freeze plug remained
intact. Thus, an evaluation of the pressure limits
created from a freeze plug application should be
based on the design limits of the piping system. It
is important in the case of double freeze plugs, or
even a single freeze plug placed next to a dead head
that their be a means of internal pressure relief of
the piping system.
Can freeze chambers be installed over a pipe weld
?
While it is possible, it is not recommended! Welds
as a rule are potential locations for flaws and
residual stresses. Depending upon the location of
the weld in relation to the freeze chamber the pipe
freeze can induce tensile or compressive stress to
the weld joint. We have no data available on the
effects that pipe freezing may have on welds. We
recommend to our clients and believe it to be just
good engineering practice not to fit our freeze
chambers on welds.
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